Found this carcass floating by Red Hook, Brooklyn, NY. It is about the size of a human torso which really freaked me out at first. But the spine is about 3 inches thick, and the ribs are too thin to be a land animal. It looks much bigger than any fish I have ever seen at New York Harbor, and unlike most fish I know of, the spine is smooth. Any suggestions on wht it may be?

PS: I walked right up to it to see if it smelled like rotten meat or rotten fish, but couldn't smell it at all. Granted, I was a bit squeamish and didn't want to get my face right in it, but no smell from about 3 feet away.